Silicon is a very common element in nature and is generally known under its natural inorganic forms such as silica and silicate, and also under the form of synthetic polymers, the silicones. These silicon-containing compounds are barely soluble or not at all soluble in aqueous medium which explains their weak incidence at the alive organisms level. The silicones, in particular, are characterized by a great inertia towards the biological medium and consequently present a high biocompatibility.
However, the silicon, even in minute quantities, plays an important biological role and must be considered as an essential element of life. It is especially necessary for a normal growth of numerous species. It has been demonstrated that silicon was intervening in the connective tissue structuration in interacting with the glycosaminoglycan and proteins. This is one of the constitutive elements of proteins-glycosaminoglycan complexes found in the extracellular matrix of these tissues. Silicon also interacts with the glycosaminoglycan in the cartilage tissue development. We also know that silicon plays an important role in the bone formation where it favours the mineralization process.
Besides, silicon can be considered as a collagen constituent and we think that it plays a major role in the reticulation process of collagen fibers. Silicon also intervenes at the hair texture level where it would especially contribute to increase the resistance of the hair fibre. Silicon is also involved in the cell metabolism and it would be especially favourable to the metabolic activity of osteoblasts.
Beyond the cross-linking power of silicon and its implication in the metabolic activity of some cells, it appears that a high silicon content, in the tissues, jointly with the glycosaminoglycan content is characteristic of healthy and metabolically active tissues. In the same way, numerous works have demonstrated the importance of silicon in the physiological cycle regulation of the hair.
Today's researches tend to reinforce the idea that silicon intervenes in numerous biological mechanisms. Recent works have even demonstrated that silicon plays a major role in the aluminum elimination by biological systems.
Works of the applicant have demonstrated that silicon compounds could constitute a form of assimilable silicon by the organism (as opposed to mineral silicon or to silicones) on condition that it possesses the characteristic of existing in aqueous solution under the form of soluble oligomers of low molecular weight. Furthermore, another necessary characteristic of the oligomers activity in aqueous solution is to present numerous Si--OH functions. So, it is evident that the biological properties of these bioavailable compounds are only observed if they form soluble oligomers in aqueous solution, which result from a chain of siloxane bonds Si--O--Si, rich in Si--OH functions.
Apart from the fact that the presence of Si-OH highly polar functions confers their water solubility to the oligomers, at the present time, we think that a part of the properties observed are conducted by the fact that the chemical species involved in most of the above mentioned biological mechanisms would be a form of soluble silicon, the silicic acid of Si(OH).sub.4 formula. This compound only exists at very low concentrations in water since it has a very strong tendency to polycondense to form silica.
Consequently we have researched more stable products similar to silicic acid, by chemically modifying the Si-OH functions. It quickly became obvious that these functions were essential for the biological activity. In other respects, we knew that a series of natural compounds, and among them, the tannins and the catecholamines were capable of forming a complex with the silicic acid and like this were capable of increasing its stability in solution. These complexes would be the way of transport for the silicic acid in the organism and it is under this form that the cell would introduce the silicon. Nevertheless, their stability is still too weak for the carrying out of a pharmacologically active product.
The applicant has perfected active analogues of these complexes. It concerns products resulting from the complexation between a complexing molecule and an active organo-silicon compound. The characteristic of these compounds is to possess several Si-OH functions like the silicic acid, but also one or two carbon-silicon bonds. Nevertheless, these analogues possessing researched biological properties, even if they are more stable than the silicic acid complexes, still they must be prepared under the form of diluted aqueous solutions, which silicon content cannot exceed 2 g/litre owing to the fact that with a higher concentration, we would favour the polycondensation.